import asyncio
from typing import Optional, Any, Dict
from ..models.schemas import ChatCompletionRequest, ChatCompletionResponse, CompletionRequest, CompletionResponse


class SGLangBackend:
    """SGLang backend implementation."""
    
    def __init__(self):
        self.supported = False
        try:
            # Try to import SGLang components
            import sglang
            self.supported = True
        except ImportError:
            pass
    
    async def load_model(self, model_name: str, model_path: Optional[str] = None):
        """Load a model using SGLang."""
        if not self.supported:
            raise ImportError("sglang is not installed. Please install it with 'pip install sglang'")
        
        model_path = model_path or model_name
        # For now, we'll just store the model parameters
        # Actual implementation would use SGLang's runtime
        return {
            "model_name": model_name,
            "model_path": model_path,
            "backend": "sglang"
        }
    
    async def unload_model(self, model: Any):
        """Unload a model."""
        # SGLang doesn't need explicit unload in simple cases
        pass
    
    async def generate_chat(self, model: Any, request: ChatCompletionRequest) -> ChatCompletionResponse:
        """Generate a chat completion."""
        if not self.supported:
            raise ImportError("sglang is not installed. Please install it with 'pip install sglang'")
        
        # This is a placeholder implementation
        # Actual implementation would use SGLang's runtime
        import time
        import uuid
        from ..models.schemas import ChatMessage, Choice, Usage
        
        # For now, return a mock response
        choice = Choice(
            index=0,
            message=ChatMessage(
                role="assistant",
                content=f"Mock response from SGLang for model {model['model_name']}"
            ),
            finish_reason="stop"
        )
        
        response = ChatCompletionResponse(
            id=f"chatcmpl-{uuid.uuid4().hex}",
            model=model['model_name'],
            choices=[choice],
            usage=Usage(
                prompt_tokens=len(request.messages),
                completion_tokens=10,
                total_tokens=len(request.messages) + 10
            )
        )
        
        return response
    
    async def generate_completion(self, model: Any, request: CompletionRequest) -> CompletionResponse:
        """Generate a text completion."""
        if not self.supported:
            raise ImportError("sglang is not installed. Please install it with 'pip install sglang'")
        
        # This is a placeholder implementation
        # Actual implementation would use SGLang's runtime
        import time
        import uuid
        
        # For now, return a mock response
        choice = {
            "text": f"Mock completion from SGLang for model {model['model_name']}",
            "index": 0,
            "logprobs": None,
            "finish_reason": "length"
        }
        
        response = CompletionResponse(
            id=f"cmpl-{uuid.uuid4().hex}",
            model=model['model_name'],
            choices=[choice],
            usage=Usage(
                prompt_tokens=len(request.prompt) if isinstance(request.prompt, str) else len(request.prompt[0]),
                completion_tokens=10,
                total_tokens=(len(request.prompt) if isinstance(request.prompt, str) else len(request.prompt[0])) + 10
            )
        )
        
        return response